Brake mechanism



' H. w. ALDEN E1- AL Feb. 20, 1945.

BRAKE MECHANI SM 2 Sheets-Shed;

Original Filed Nov. 14, 1941 /feferf WAI/den 7M/rence R 50c/renda@ ama/mia.

Feb. 2o, 1945. H w, ALBEN ET AL Re. 22,604

' BRAKE MECHANISM Original Filed Nov, 14

2 *Sheets-Sheet 2 .l .5 Isl-al.

named Feb. zo, 194s Re. y22,604

Herbert W. Alden, Lawrence R.

Ralph K.

Buckendale, and

Super, Detroit, Mich., assignors to The Timken-Detroit Axle Company, Detroit, Mich., a corporation of Ohio original No.

2,337,010, dated December 21, 1943,l

Serial No. 419,198,- November 14, 1941. Application forrelssue August 30, 1944, Serial lNo.

20 Claims.

I'he present invention relates to brake mecha.- nisms, and more particularly to brake mechanisms for automotive vehicles, although it is not limited to such use.

In the co-pending application of Spiller et al., Serial No. 387,314, filed April 7, 1941, for Brake mechanism, there is disclosed a brake mechanism embodying a pair of floating shoes which coact with fixed abutments in such manner that both shoes function as "leading shoes in either direction of drum rotation, and each shoe manifests a predetermined degree of self-energization.

(Cl. 18S- 78) While the brake mechanism disclosed in the aforementioned co-pending application, constituted a substantial advance in the art, it was found that the shoes did not exert exactly the same braking action in both directions of drum rotation, the forward shoe showing slightly greater wear at the heel.

It is accordingly the major object of this lnvention to provide a novel brake mechanism which possesses all of the advantages of the brake mechanism of the aforementioned application, overcomes the disadvantages of that brake mechanism, and possesses further important advantages to vbe hereinafter pointed out.

A further object is to provide a brake mechanism embodying floating shoes whose opposite ends abut link members pivoted upon anchor pins, and to so locate the anchor pins and to give the abutment faces the proper inclination, and to apply forces to the brake shoes in such manner, as to achieve substantially uniform braking characteristics and brake lining wear at R 'both ends of the shoes, in either direction of drum rotation.

Another important object is to provide a brake mechanism having means for adjusting the shoes toward the drum, to compensate for wear of the lining, which is so designed that the center of the shoe is moved approximately twice as far as possible with the brakes heretofore proposed.

A further object is-to provide a brake mechap nism having a floating shoe actuated by a'fulcrumed lever, with means for simultaneously displacing one end of the shoe and the fulcrum point .of the lever, in directions to move the shoe toward the drum, for compensating for lining wear.

It is another object' to provide an improved device for transmitting forces from the brake actuating lever to the .brake shoe, which embodies a large area curved face coacting in rocking'l surface engagement with the shoe, and a large area flat face coacting in sliding surface engagement with the actuating lever. A

A further object isto provide an actuating lever assembly. which will exert a compounding or force multiplying action upon the shoe.

Further objects are to provide an improved retracting spring assembly for the lower ends of the shoes, and an improved guiding assembly for the mid-portion of the shoes and levers, to insure lateral stability under all operating conditions, and to generally improve andrene certain other features of the brake mechanism of the aforementioned application, as will hereinafter appear.

Further `objects will become apparent as the specication proceeds in conjunction with the annexed drawings and from the appended claims.

In the drawings:

Figure 1 is an end view of a brake mechanism embodying the present invention-only one-hall of the brake being shown, to simplify the disclosure,. and certain parts being removed, t0 more clearly illustrate the construction involved;

Figure 2 is a sectional view taken substantially along the line l2 1 of Figure 1, viewed in the direction of the arrows;

Figure 3 is a sectional view taken along the line 3--3 of Figure 1, looking in the direction of the arrows; and

Figure 4 is a View 'of one of the eccentric anchor pins.

With continued reference to the drawings, in which similar reference characters have been employed to designate like parts throughout the several views thereof, the brake mechanism broadly comprises a pair of brake shoes A mounted for movement toward and away from a brake drum B, each brake shoe being actuated by a pair of leversC, which in turn are actuated by any suitable form of mechanism, such as the hydraulic or pneumatic piston and cylinder assembly D or by a cam or the like.

All of the working parts of the brake are carried by a backing or foundation plate Ill, which ,is provided with a peripheral dirt excluding lip Il, and a central opening l2. Y The foundation plate is adapted to be mounted over an axle in well known-,mannen with the portion of the plate adjacent opening i2 abutting a flange on the axle, and `secured thereto by screws or rivets passing through openings I3 in the plate.

Since the mechanism is exactly symmetrical, and the other brake shoe and lever assemblies are identically the same, only vone of them has been shownin order` to simplify the disclosure. The novel mounting of the brake shoe will now be described.

Rigidly secured to backing plate III is a pair of anchor pins l5 and IB. Pin I5 is provided with a pair of small diameter eccentric portions I'I and I3 and an intermediate large diameter eccentric portion l5. A flange 2li on the pin is pulled into 4tight engagementy with plate I0 by means of a nut 2|. Flange 20 may be provided with serrations matching with similar serrations on plate ID so that when the parts are pulled into tight engagement, the pin is positively locked against rotation. Pin I3 is secured in place by a nut 22. l

By mounting the brakeshoe abutments and acuating levers upon eccentrics I1, I8 and I9, as hereinafter pointed out, it is possible to simultaneously displace them in novel manner to advance the shoe toward the drum and compensate for brake lining wear. Pin I5 is lprovided .with a squared-end, so that by loosening nut 2| the pin may be engaged by a wrench and turned to rotate the eccentric, and thereby adjust the brake in 'a manner to be hereinafter pointed out.

Upper pin I5 is provided with a shoulder 23. which is pulled into tight engagement with a reinforcing plate 3i, secured in turn to backing plate Il) by means of rivets 32. Pin I5 is provided with a smooth journal portion 33 upon v which one of the abutment members is pivoted as will now be described.

Anchor pins I5 and I5 constitute the sole support for the shoe and actuating lever, and by locating the anchor pins in substantial vertical alignment, substantially equally spaced from a horizontal centerline containing the axis of drum rotation, as shown in Figure 1; inclining the abutment faces on the ends of the shoe so as to intersect closely adjacent the horizontal centerline, and applying the braking forces at the mid-portion of the shoe by a device having a rocking axis located closely' adjacent the vertical centerline of the anchor pins, as will now be specically pointed out, a brake mechanism Vis provided which possesses substantially identical braking characteristics for both directions of drum rotation, and in which both shoes function as leadingshoes and manifest a definite controllable degree of self-energization, and the pressure on the shoes is so distributed as to effect equal wear of the lining at both ends of the shoe.

The brake shoes B may be provided with the usual liningy material in conventional manner, but they are preferably constructed in accordance'with Alden Patent No. 2,167,607, dated July 25, 1939, and have an outer portion 35 which is so shaped that when the lining material 35 is j in place, having its outer surface conforming to the shape of the drum, it is of crescent shape in cross-section. with the thickest portion of the lining in the middle of the shoe, where the greatest wear occurs.' Therefore, as the lining wears down, even though it wears the greatest degree in the middle of the shoe, at the end of its useful life it will be worn down to all of the rivet heads simultaneously, and maximum use made of the lining material. By reason of the novel adjusting feature of the invention, which provides fora large compensating travel of the shoes, the lining may, if desired, be of three-quarter inch thickness.

The shoe has a central web or flange 31v provided at its opposite ends with abutment faces 33 and 39, which cooperate with link or abutment members 4I and 42, respectively. The abutment members are carried by the anchor pins, and directly absorb the braking torque reaction of the drum in both directions of rotation. Abutment member 4I is pivoted upon eccentricportion I9 of anchor pin I5, so that by rotating the anchor pin, as will be hereinafter described, the abutment member is displaced so as to advance the lower end of the shoe with respect to the drum and take up the clearance caused by lining wear. The upper abutment member 42 is pivoted upon journal portion 33 of anchor pin I6.

The coactinng faces of the abutment members are comparatively long, so as to avoid high localized pressures, and to also insure proper plvotal movement of the abutment members in response to the application of the drum reaction forces thereto, and` prevent the abutment members from swinging around and locking the shoes in engaged position. The lower end of the brake shoe terminates in an eyev 44 into which the end of a tension spring 45l is hooked. The other end of'the spring is similarly connected to the other shoe of the brake not shown. It was found possible to employ a single spring 45 to retract l the brake shoe, because the downward action of the gravity upon the shoe, in combination with the horizontal pull of spring 45, results in a returning action substantially at right angles to the abutting face.

By locating the anchor pins in vertically spaced relationship as shown, symmetrically disposed at either side of the horizontal centerline axis and employing the force transmitting mechanism between the lever and the shoe which will now be described, and having an effective rocking axis located closely adjacent the anchor pin centers, a brake vmechanism is provided having substantially identically the same operating characteristics for both directions of drum rotation, with the wear at one end of the shoe being no greater than the wear at the other, with the result that the lining wears away evenly and a maximum use is made thereof.

A pair of levers 5l and 52, of substantially identical shape, (lever 5l has been removed in Figure 1), are secured together in spaced parallel relationship by means of a block 53, rigidly secured in place between the levers by lmeans of a weld 54, and by a shouldered stud 5G riveted to the upper ends of the levers. Levers 5I and 52 are journalled upon the small diameter eccentric portions II and I8, respectively, of anchor pin I5. The lever assembly is detachably secured in place on the lower anchor pin by means of a Washer 51 and a splitnring 59, which is sprung into a groove in the anchor pin.

By reason of the novel double eccentric construction of anchor pinA I5, the latter may be rotated s o as to displaceboth of the rocking axes of member 4I and levers 5I and 52 in a direction in Figure 2, a shoulder 63 on the pin restrains l the lever assembly against movement to the right. and the snap-ring assembly just described prevents movement of the lever assemblyin the opposite direction.

The upper end of the shoe is urged towards disengaged position by means of a short link member 66 having one end hooked into a bore 66 in the brake shoe web andvprovided at its free end with an eye 61. vA somewhatl similar link member 66 is hooked into an opening 66 in the upperend of lever 52 and is provided at its free end with 'an veye 1I. A tension spring 12 is hooked into eyes 61 and 1i at one end, and at the other end is hooked into the corresponding eyes of the opposite brake shoe and link assembly. The spring, acting through the links, constantly urges the brake shoe away from the drum and toward engagement with its abutment link l2. The spring also urges the lever assembly into retracted position, link 68 confining pull of spring 12 upon link 65 to a direction substantially normal to face 39, with the result that there is no tendency to slide the upper end of the shoe across the face of member 42. Opening 69 is located as close to the centerline of pin 56 as practicable, to prevent any tendency for the brake to drag.

The brake shoe actuating levers just described may be operated by hydraulic, pneumatic or mechanical means of any desired character, it only being necessary to spread the upper ends of the levers to actuate the brake. `In the present instance, however, we have illustrated a well known type of hydraulic mechanism embodying a cylinder 14 having a piston in each end thereof. A

piston rod in the form of a short link 15, seating in a socket in the piston, is provided with a forkedportion 16, which ilts over, and fulcrums v against spacer pin 56.t The hydraulic cylinder is also provided with a sheet metal shield 11, which protects the cylinder from the radiant heat of the drum and keeps the iluid below the boiling point.y 'I'his precludes destruction of the rubber parts in the unit.

When pressure is applied to cylinder 14, links 15 move outwardly and cause the levers to fulcrum about the lower anchor pin eccentric portions as axes. Rocking movement of the levers is transmitted to the brake shoes by a novel fulcrum assembly, which applies the forces substantially centrally of the shoe, permitting free rocking or floating of the shoe into full surface engagement with the drum, and also embodying a force transmitting member having an effective center of rotation located closely adjacent the centerline of the two anchor pins.

The brake shoe web is providedwith an accurately formed cylindrical vseat 18, whose center of curvature 19 lies substantially on the line 8| joining the centers of the anchor pins. A force f transmitting member 82,4 shaped similarly to a woodrufl.' key, has a curved face accurately fitting recess 1B and a flat face B3 adapted for sliding engagement with an accurately formed flat face 8| provided on block 53. As seen in Figure.

3, member 62 is conned between levers ll and Il, and` therefore requires no retaining means to keep it in place.

Member. 62 provides a large area curved surface engaging the brake shoe and a large area flat surface engaging member 63, and as the latter is rigidly joined to both levers throughout comparatively long portions, it is apparent that the forces developed in the levers, as a result of actuation of the l'wdraullc cylinder, are distributed over a large area and uniformly transmitted to members 53. The forces transmitted to the large area bearing surface of member 62 are in turn transmitted through its large area -curved surface to the brake shoe, while permitting the shoe to freely align itself with the drum, and at the same time member 62 may freely slide on member il to compensate for the offset of the y aexs of the lever and link 4I'.

The novel lever and force transmitting assembly just described also possesses the advantage of providing a definite degree of compounding. As seen in Figure 1, the distance from point 19 to the axis of eccentric portions I1 and I8 of anchor pin I 5 is less than the distance from point v 16 to the axis of pin 56, with the result that the assembly possesses a mechanical advantage and the application of a force of predetermined magnitude upon-pin 56 will be reflected as a force of greater magnitude upon the brake shoe. The novel lever assembly will accordingly exert a greater force upon the brake shoe than the assemblies of the prior art, with a cylinder of given size.

If desired, the mid-portions of each shoe. may be further stabilized against axial displacement by means of a screw B5, having a shoulder 86.

pulled into tight engagement with a pressed in.

or embossed portion 61 of plate i0, by means of a nut 89. Screw 85 extends through enlarged openings 90 and 9i in levers 5I and 52respec tively, and through a large opening 92 in the brake shoe web, so that'the pin will not in any way interfere with movement of the brake shoe or levers. A washer`93 is located under the head of the screw and cooperates with lever 5I, it being understood that the parts are so dimensioned that a. slight axial play is permitted when the screw is pulled up tight. The embossed portion 81 of plate Ii) limits movements of the parts in one direction, and the head of the screw limits movement in the opposite direction.

Thebrake mechanism embodies a shifting anchor pin for each shoe, with the result that when the brake is actuated with the drum rotating in one direction, the drum reaction is taken by one set of anch'or pins, and when the direction of drum rotation is reversed, the drum reaction is taken by the other pair of anchor pins. The brake mechanism of the aforementioned pending application also embodied a shifting anchor pin asvsembly, but in the present mechanism the parts coact in a somewhat different relationship to modify the action of the mechanism. By locating the a'nchor pins symmetricallyeither side of a horizontal line containing the drum axis; ap-

plyingthe lining to the shoes so as to be substantiauy bisected by the horizontal line; inclinmg' faces 38 and 39 so as to intersect at a point on lthe horizontal'centerline; and applying the braking forces to the shoe by means of a rockable device having an effective-axis located closely adjacent the centerline of the anchor pins, the

I brake mechanism Vof this invention provides sub- -stantially identical operating characteristics in Operation l Assuming that the drum is rotating in counter clockwise, (Figure 1) andhydraulic or penumatic pressure is applied to cylinder 14, link 15 moves outwardly and rocks the lever assembly shown counterclockwise about the axis of eccentric portions i1 and I8 of anchor pin I5. This action, through member v82, forces the brake shoe outwardly toward the drum against the action of springs 45 and 12. As soon as contact of the shoe is made with the drum, the shoe rocks slightly into the proper position to bring it into full surface engagement with the drum, and simultaneously the shoe is displaced a slight distance in a counterclockwise direction to bring its abutment face 38 into firm engagement with link.

II, coacting faces B3 and B4 freely sliding upon each other as this takes place. shoe (not shown) functions in exactly the same way for clockwise rotation of the drum as the illustrated shoe for counterclockwise rotation, since the levers are fulcrumed to the same side of the axis of drum rotation.

The opposite Assuming that the drum is rotated in the opposite direction, namely, clockwise as viewed in Figure land the brake actuated as before, the drum reaction forces the brake shoe angularly in a clockwise direction, so as to bring surface 39 into tight engagement with abutment member 42. This transmits the braking reaction forces applied to the shoe to anchor pin IB. The eiective anchor for the brake shoe hastherefore been shifted or transposed, through reversal of rotation of the drum, from pin I5 to pin I6, andall of the advantages of the leading shoe, which includes a desirable degree of self-energization are realized for both directions of drum rotation.

Upon conclusion' of the braking operation, pressure is released from cylinder 14 and springs 44 and 12 return the shoes and levers to inoperative position, spring 12 acting through links 65 and 58 to return the upper ends of the shoe and levers, while spring 45, acting in conjunction with the downward pull of gravity upon the shoe,

effectsV a substantially radial inward return of the lower end oi' the shoe.

The geometry of this brake is the same as that for the brake of the aforementioned co-pending application. However. in order to show the somewhat different manner in which the forces actv upon the parts in the present mechanism, lines have been indicated in Figure 1 as follows. For either direction of drum rotation three forces act upon the shoe, namely, (1) the actuating force P, acting throughmember B2 substantially at the mid point of the shoe, and directed substantially along the horizontal center line; (2) the thrust or torque reaction Q-I or Q-2, depending upon the directonof rotation of the drum, and acting at 90 to the particular anchor pin involved; and (3) the resultant drum reaction R, passing through the intersection X of Q1 and Qa.

The force'diagram may be solved vectorially in wellvknown manner to locate the point X, it being understood that the distance of point X from the axis of drum rotation will depend upon the co-emcient of the brakelining material employed. -The resultant force diagram shows that the brake is perfectly symmetrical, pins I5 and I6 being disposed equal distances on opposite sides of the center line, with the result that angles Y and Z are exactly equal; and Q1 and Q: are of equal length. It has been found in practice that the brake has identically the same operating characteristics in both directions of drum rotation and that no greater wear is produced on one end of the shoe than the other.

Brake adjustment If after the brake has been in use for sometime the lining becomes so worn as to introduce an undesirably large clearance between the lining and the drum, each nut 2I is loosened sufficiently to disengage the serrations of iiange 20 from the serrations in plate I 0, and the anchor pins are rotated to take up the clearance in novel manner, it being understood that the pin I5 shown will be rotated counterclockwise, while the opposite lower pin (not shown) willbe rotated clockwise to take up the lining wear.

Referring to Figure l, the axis of eccentric I9 is oiiset further from the axis of theanchor pin than eccentric portions I1 and I8, with the result that when the pin is rotated to take up for wear. abutment member II and the lever assemy bly will be simultaneously pulled upwardly and to the left, butmember All will be Amoved a greater distance, by reason-oi.' the greater oifset from the axis. Eccentric portions I1 and I 8 are also oifset in a counterclockwise direction from por- .l tion I9, for a purpose that will presently appear;

Moving linkmember 4I as just described in effect reduces the angular distance between abutment a faces 38 and 39, and results in movement of the brake shoe toward the drum, and simultaneously, movement of the lever upwardly and slightly to 'the left, has the effect of lengthening the mewchanical connections from link 15 to the brake shoe, with the result that rotation of the anchor pin as just described results in a compound or a multiplied displacement of the brake shoe in a direction to compensate for brake wear.4

It is accordingly apparent that a comparatively small angular movement of the lower anchor pin results in a comparatively large displacement of the brake shoe, as compared with the prior art brakes, in which the thickness ofv the brake liner is limited to the available stroke in the wheel cylinder, and in which adjustment of one end of the brake shoe results in displacing the center of the shoe only half as far as that achieved in the novel construction just described. This makes it possible to use a thicker lining than has heretofore been feasible.

It is to be observed in Figure 1 that three successive adjusted positions of pin 56 are represented by the illustrations 56, 5Ib and 56, it being understood that the first position corresponds to a new" lining, the second position corresponds to a partially worn lining, and the third corresponds to a lining which is substantially completely vworn out. The second and third positions of the pin areillustrated as the parts appear when the brake is applied. We have found that by initially adjusting anchor pin I5 into the full line position shown in Figure 1, and offsetting eccentric portions I1 and I3 from portion I9 as shown, it is possible to successively adjust it through the life of the brake lining until it has been rotated through almost without in any way interfering with the proper cooperation of pin 56'* and link 'l5 with the hydraulic cylinder, since the vertical travel is distributed to either side of the centerline of the hydraulic cylinder. That is, in the first position (55), the pin 55 is disposed below the centerline, in the second position (56h), it is disposed above the centerline a substantially equal distance, and in the third position,V (55), it is again disposed below the centerline. This precludesrocking of parts into a position that would produce undue angularity of link 15 with respect to the piston.

When the adjusting operation just described has been completed, nuts 2| are then tightened, so as to securely interlock the serrations of anchor pin I5 with foundation plate, and the brake is again ready for service.

Although the novel double eccentric adjustment of the inventionhasbeen speciiically disclosed as embodied in the particular symmetrical brake illustrated, it is to be understood that the novel brake adjustment is also useful in other types of iloating shoe brakes. for instance; it may be advantageously employed in the brake of the aforementioned co-pending application, or other brakes in which the brake shoes are mounted for floating movement alternately into engagement ywith anchor pin assemblies or the like, located at each end of the brake shoe, and the appended claims are intended to embrace the invention when it is employed in such brakes.

From the' foregoing detailed disclosure of the invention it is apparent that we have provided a novel `brake mechanism which, by reason of the novel manner of applying the braking forces to the brake shoe: the placement of the anchor pins symmetrically with respect to a horizontal centerline through the .drum axis; designing the shoes so as to be substantially bisected by the center-line; the symmetrical inclinations given the abutment spaces of the brake shoe so as to intersect at a point on the horizontal centerline, the brake possesses identical braking characteristics in both directions of drum rotation,and the wear on the lining is absolutely uniform, and also by supporting the lower abutment members and the levers upon la double eccentric anchor pin, it is possible to simultaneously adjust or displace abutment member and the lever fulcrum point in such a manner as to move the brake shoe toward the drum for brake adjusting purposes a materially'greater' distance than in the brakes of the prior art.` f The invention may be embodied in other specic forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in'all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by .United States Letters Patent is:

l. In a brake mechanism adapted to be operatively associated with a brake drum; means mounting a brake shoe and a brake actuating lever for movement toward and away from said drum about predetermined axes, means for rocking said lever; means for transmitting forces from said lever to said brake shoe when said lever is rocked; and adjusting means for simultaneously displacing said axes 1n a direction to compensate for wear of said .brake shoe.sald adjusting-means being operable .to displace said axes by runequal y' amounts. n

2. In a brake mechanism adapted to be operatively associated with a brake drum; a foundation structure forlsaid mechanism an anchor pin carried by said structure and mounted for rocking movement aboutits axis into a plurality of ad- Justed angular positions; an abutment member .adapted to apply -pivoted on said anchor pin; a brake shoe mounted for movement toward and away from said drum and having an abutment face adapted to apply reactive forces to said anchorpin through said pivoted'member when said brake shoe is engagedl 154 with said drum; a lever-fulcrumed on said anchor pin; means for rocking said lever: means for transmitting forces from said lever to said brake shoe when said. lever is rocked; and adjusting means for varying the fulcrum point of said lever to compensate for wear of said brake shoe when said anchor pin is adjusted angularly.

3. The brake mechanism defined inl claim 2,

wherein said adjusting means is also operable to advance said shoe toward the *drum when said anchor pin is adjusted angularly. l

4. In a brake mechanism adapted to be operatively associated with a brake drum; a foundation structure for said mechanism; an anchor pin having an eccentric portion and carried by said structure for adjustment into a plurality of an x gular positions a brake shoe mounted for movement toward and away from said drum and reactive forces to said anchor pin when it is engaged with said drum; and a lever fulcrumed on anchor pin and having force transmitting means associated therewith operable to apply braking forces to said brake shoe when said lever is rocked. saideccentric portion of said anchor pin being operable to displace the fulcrum point of said lever to compensate for wear or said brake shoe when said anchor pin is adjusted angularly.

5. In' a brake mechanism adapted to be operatively associated with a brake drum; a stationary support for said mechanism; an anchor pin mounted on said support for adjustment into a plurality of angular positions about its axis and .ing said anchor pin, for simultaneously adjusting said lever and shoe 'in directions to rcompensate for wear of said brake shoe."

6. The brake mechanism dened in claim 5, wherein said eccentric portions are disposed different distances from the axis of said anchor pin ai are angularly offset with respect to each o er.

7. In a brake mechanism .adapted to be operatively'associated with a, brake drum; a, pair of anchor pins circumferentially spaced with respect toisaid drum and each pivotally carrying an abut ment member; a brake shoe mounted for floating movement toward and away from said .drum and having inclined abutment faces adjacent its ends coacting with said abutment members; means for increasing or decreasing the circumferential spacing of said anchor pins, so as to adjust said shoe toward and away from said drum; a lever the eccentric portion of said r pivoted adjacent one end of said shoe and` operable to engage said shoe with the drum; and means for displacingthe pivot point of said lever -so as to advance said shoe toward said drum, to

' ing movement thereof and adjusting means for displacing the rocking axis of the fulcrumed end of said lever so as to advance said shoe toward the drum, to compensate for brake wear, said adjusting means being operable to advance the free end of said lever first to one side'and then the other of the line of action of said actuating means in response to successive brake adjustments. 9. In a brake mechanism adapted to be operatively associated with a brake drum; apair of anchor pins mounted in circumferentially spaced relationship with respect to said brake drum; an abutment member pivoted on each of said pins; a brake shoe mounted for movement toward and away from said drum and having an abutment face adjacent each end adapted to engage said abutment members during brake operation; and lever means for engaging said shoe with said drum; said abutment faces being so inclined that when produced they intersect a radial line at a J point between said shoe and the axis of said drum, and said shoe having an eifective frictionai area which is substantially bisected by said radial line, whereby said brake shoe will manifest substantially identical braking and wear characteristics'for both directions of drum rotation, said lever means being fulcrumed adjacent one end of said shoe and being operable to apply brake engaging forces to the intermediate portion of said shoe along said radial line.

10. In a brake mechanism adapted to be operatively associated with a brake drum; a pair of anchor pins mounted in circumferentially spaced relationship with respect to saidbrake drum; an abutment member pivoted on each of said pins; a brake shoe mounted for movement toward and away from said drum andA having an abutment face adjacent each end adapted to engage said abutment members during brake operation; and

means, including a lever, for engaging said shoev with said drum, said means comprising a part having slidable engagement with said lever closely adjacent a plane containing the axes of said anchor pins; said abutment faces vbeing so in- `clined that when produced they intersects. radial line at a point between said shoe and the axis of said drum. and said shoe having an effective frictional area which is substantially bisected by said radial line, whereby said brake shoe will manifest substantially identical braking characteristics for both directions of drum rotation.

11. In a brake mechanism adapted to be operatively associated with a brake drum; a pair of circumferentially spaced anchor pins mounted in xed relation in said mechanism; a brake shoe mounted for movement toward and away from said drum and having means at the ends thereof vadapted to apply reactive forces to said anchor pins during brake application; a lever journalled for rocking movement toward and-away from said shoe; and means, having a rocking axis located `'atively associated with a brake drum; a pair of circumferentially spaced anchor pins mounted in fixed relation in said mechanism; a brake shoe mounted for movement toward and awafy from said drum and having means at vthe ends thereof adapted to apply reactive forces to said anchor pins during `brake application; a lever journalled for rocking movement toward and away from said shoe; and means, having a rocking axis and a at force transmitting face located closely adjacent a plane containing the axes of -said anchor pins, for transmitting braking forces to the mid-portion of said brake shoe when said Llever is rocked.

13. In a brake mechanism adapted to be operatively associated with a brake drum; a brake shoe I mounted for movement relative to said drum; an actuating lever pivoted for rocking movement adjacent one end of said shoe; means for rocking said lever; and means for transmitting forces from said lever to said brake shoe. comprising amember having a curved surface seating in a recess in said shoe and having a flat surface slidingly abutting a fiat' surface provided on said lever.

14. In a brake mechanism adapted to be operatively associated with a brake drum; a brake shoe mounted for .movement relative to said drum; an actuating lever p'ivoted for rocking movement adjacent one end of said shoe; means for rocking said lever; and means for transmitting forces from said lever to said brake shoe,4

directed web; a lever fulcrumed adjacent one end of said shoe and made up of two parts, one disposed either side of said web; means for securing said lever parts together comprising a member disposed between said parts and pref senting a at face directed toward said web; said web having a'curved face disposed opposite said member; and a force transmitting element disposed between said webs and having a curved surface engaging the curved face of said web, and a fiat surface disposed in sliding engagement with the fiat face of said member.

16. In a brake mechanism adapted to be operatively associated with a brake drum; a brake shoe mounted for floating movement toward and away from said drum and adapted to transmit rotative thrusts to a pair of anchor pins carried by a stationary plate; said shoe having a web projecting inwardly 'between a pair of actuating levers; and means for' stabilizing said shoe and levers and limiting axial movement thereof, committing relationship with said anchor pins in either direction of drum rotation. l

17. In a brake mechanism adapted, to Ibe operatively associated with a brake drum; a support for said mechanism; a pair of circumferentially spaced anchor pins mounted on said. support; an abutment member pivoted on each pm; a brake shoe mounted for oating moveends when .the lever is rocked; means mounting said one pin for angular adjustment about its axis; and cam means on said one pin for simultaneously adjusting said lever and shoe in directions to compensate for brake shoe Wear When said one pin is angularly adjusted.

18. For use in a brake mechanism of the type wherein a friction brake shoe is operatively connected 'by a motion transmitting connection to an actuating lever therefor pivoted at one end adjacent an end of said shoe and wherein said shoe has spaced surfaces cooperatively engaged with abutments in said mechanism in such mannerthat the same motion transmitting connection in association with said abutments permits controlled rocking movement of said shoe during braking operations; a brake shoe member comprising a web having an arcuate iiange upon which a lining of friction material is secured, an arcuate recess in the side of said member oppovsite said iiange functioning as part of said motion transmitting connection, and means providing circumferentially spaced angularly disposed abutment surfaces on said shoe adapted and shaped to engage said abutments, said web being apertured intermediate said flange and said arcu-4 ate recess for operative interconnection with said actuating lever.

19. For use in a brake mechanism of the type wherein a friction brake shoe is operatively connected by a motion transmitting connection to an actuating lever therefor pivoted at one end adjacent an end of said shoeand wherein said fil.

shoe has spaced surfaces cooperatively engaged with abutments in said mechanism in such manner that the said motion transmitting connection in association with said abutments permits controlled rocking movement of said shoe during braking operations; a brake shoe member comprising a web having an arcuate flange upon which a lining of friction material is secured,

an arcuate recess in the side of said member opposite said ange functioning as part of said motion transmitting connection, and means providing circumferentially spaced anguiarly disposed substantially planar abutment surfaces on said shoe adapted and shaped to engage said abutments, said shoe abutment faces being located adjacent opposite ends of said shoe member and so disposed that the intersection of projections of the planes thereof includes a 'point substantially on a radius of said flange, and said web being apertured intermediate said flange and said arcuate recess for operative interconnection with said actuating lever.

20. For use in a brake mechanism ofthe type wherein a friction brake shoe is operatively convnected rby a motion transmitting connection to an actuating lever therefor pivoted at one end adjacent an end-.of said shoe and wherein said shoe has 'spaced surfaces cooperatively engaged with abutments in said mechanism in such manner that the said motion transmitting connection in association with said abutments permits controlled rocking movement of said shoe during braking operations; a brake vshoe member comprising a web having an arcuate iiange'upon which a lining of friction material is secured, an arcuate recess in the sideof said member opposite said flange functioning as part of said motion transmitting connection, and means providing circumferentially spaced angularly disposed abutment surfaces on said shoe adapted and shaped to engage said abutments, said web being provided with means intermediate said flange and said arcuate recess for operative interconnection with said actuating lever.

HERBERT W. ALDENA.

LAWRENCE R. BUCKENDALE.

RALPH K. SUPER. y 

